1. Field of the Invention
This invention relates to a mixing chamber for use with electric arc heaters for damping flow perturbations and vortices in heated gas streams to produce smooth flowing gas streams.
2. Description of the Prior Art
Many industrial processes require large volume streams of gaseous reactants to be heated to high temperatures in order to supply the thermal demands of particular processes. In general, it is desirable to supply the required energy without contaminating the reactant stream, and thus elaborate and generally complex heat exchange devices are frequently used. A typical example is a process for production of titanium dioxide pigment. For this endothermic reaction, titanium tetrachloride (TiCl.sub.4) is heated to a temperature of about 1000.degree. C. and combined with oxygen which is preheated to about 1200.degree. C. The oxygen is heated in an externally fired heat exchanger to the maximum achievable temperature with state of the art materials. Inconel is typically used. Titanium tetrachloride, being corrosive at elevated temperatures, cannot be contained in conventional metals, and requires a very complex and delicate externally fired serpentine heat exchanger in which the TiCl.sub.4 is contained in fused quartz tubing. Variations in flow and resultant pressure drop in the downstream reactor and coolant sections often produce acoustic waves which cause vibrations in the delicate quartz serpentine. Rupture occurs when the resonant frequency is reached, resulting in expensive maintenance and loss of production.
The titania industry has attempted many process variations to circumvent the problems, but each has significant disadvantages. Fuel oil has been admixed with the hot oxygen, thus reducing the temperature requirement for the TiCl.sub.4 to a level suitable for conventional materials. Fuel combustion increases the mass requirement for oxygen substantially, and produces copious quantities of HCl upon reaction with the TiCl.sub.4. The HCl is very corrosive to the downstream materials of construction and furthermore, it cannot be recycled for subsequent reuse.
Another process employs the combustion of carbon monoxide to provide the superheat energy, but it too suffers from increased costs of both oxygen and carbon monoxide. In another process, the oxygen is heated to temperatures of about 2000.degree. C. by passing it through the discharge in a D.C. electric arc heater. This circumvents the need for the delicate quartz superheater for the TiCl.sub.4 as the heat of reaction enters the process by superheat of the oxygen. The disadvantages of that process are limited production volume, employment of an expensive D.C. power system to supply the arc heater, and the geometry not being suitable for conversion of existing gas fired processes.